Mathur said dozens of bodies have been recovered from the burned-out coaches.

Sriprakash Jaiswal, India's junior home minister, said the bombs were not powerful, and were simply intended to start a fire "as part of a conspiracy."

"The purpose is to disturb communal harmony, India's stability and to disturb the peace process between India and Pakistan."

The Samjhauta Express, which connects the capital to the northern Pakistani city of Lahore, was en route to Attari, the last station before the border with Pakistan, where passengers alight and cross the border on foot before boarding another train to complete their journey.

Train sealed

Indian television channels showed rescue workers sifting through the charred remains of the carriages.

Because of security concerns, trains are often kept sealed with doors locked and bars over many of the windows, it is thought many passengers may have been trapped inside the burning cars.

However many Indian trains also suffer from chronic overcrowding with passengers often hanging outside the carriages.

An Indian news channel reported that petrol bombs caused the deadly explosion [AFP]

India's Times Now news channel said two petrol bombs were believed to have exploded, adding that it took one and a half hours for rescue workers to arrive at the scene at the village of Deewana, five kilometres from Panipat.

A top state government official said most of the victims were Pakistanis but included some Indian security personnel.

"We condemn this act of terrorism in which many precious lives have been lost," said Tasnim Aslam, a spokeswoman from Pakistan's foreign ministry.

"It is the responsibility of the Indian authorities to provide security to the train inside Indian territory. We expect Indian authorities to punish the perpetrators," she said.

The fire immediately evoked memories of a fire aboard another train in the western state of Gujarat in 2002.

It triggered one of India's worst outbreaks of sectarian violence in recent years, as Hindu mobs went on the rampage leaving more than 1,000 people dead, most of them Muslims.

Visit still on

Meanwhile Pakistan said its foreign minister would go ahead with a trip to India on Tuesday as planned.

Hkursheed Mahmoud Kasuri is due to meet his Indian counterpart for talks on the tentative peace process between the two countries.

"This kind of incident can't stop good and positive relations between India and Pakistan," said Sheikh Rashid Ahmed, Pakistan's railways minister, although he added security would be increased on the Pakistan part of the line.